The value of the missing length is 20
Let the missing length be x
From Parallel lines and transversal theorem, we have that
If three or more parallel lines intersect two transversals, then they cut off the transversals proportionally.
Then, we can write that

∴ 
x = 20
Hence, the value of the missing length is 20
Learn more here: brainly.com/question/24258397
Step-by-step explanation:
in a geometric sequence there is a constant factor x that is multiplied with every previous term to create the next one.
a2 = 20
a5 = 1280 = a2×x×x×x = a2×x³ = 20x³
64 = x³
x = 4
=> a1 = 5
therefore
an = an-1×4 =

n > 1
12 and 1/8, I just simplified 2/16 to 1/8
B=8. A^2+B^2=C^2. This means 6to the second power plus B to the second power equals10 to the second power. 36+b^2=100. B to the second power equals 64. Square root of 64 is 8, so B equals 8